1. Technical Field
The present invention relates to an image forming apparatus belt, a belt stretching device, and an image forming apparatus.
2. Related Art
As an image forming apparatus using an electrophotography system, for example, there is a color image forming apparatus of an intermediate transferring system using an intermediate transferring belt. In this apparatus, the intermediate transferring belt is rotated while contacting a transferring portion of an image bearing body (e.g., a photosensitive drum) on which a toner image is borne by an electrophotography process, or the like, and this intermediate transferring belt is provided such that this belt is stretched on a plurality of belt supporting rollers. A plurality of toner images borne on the image bearing body are primarily transferred once such that these images are superposed on the same position of the intermediate transferring belt, and then the toner images transferred on the intermediate transferring belt are secondarily transferred at a time onto a paper. Then, the multicolor toner image being secondarily transferred onto the paper is fixed by a fixing device to form a color image.
In addition, as an image forming apparatus equipped with another belt, there is the so-called tandem type color image forming apparatus using a paper conveying belt that holds a paper and coveys the paper to pass through transferring portions of a plurality of image forming units. In this apparatus, a plurality of image forming units for forming a toner image in each color component individually are aligned, and then the paper conveying belt is stretched on a plurality of belt supporting rollers such that this belt is rotated while contacting transferring portions of respective image forming units. The paper being sucked and held by the paper conveying belt is conveyed to pass through the transferring portions of respective image forming units. Thus, respective toner images formed by the image forming units are transferred onto the same paper such that they are superposed sequentially, and then fixed finally to form the color image.
In the image forming apparatus equipped with such intermediate transferring belt or such paper conveying belt, the high-precision position control is indispensable in superposing the images precisely. In the related art, the position control of the belt is made by detecting a predetermined position of the belt by a sensor.